The present invention relates to clay moulding apparatus and in particular to apparatus for supplying clay lumps to successive mould trays.
In particular a supply of clay is formed into individual lumps and deposited side-by-side into mould cavities of a tray conveyor. The apparatus has at least one extruder and the lumps are deposited by two cooperating, substantially vertically positioned conveyor belts located beneath the nozzle of the extruder.
Clay moulding apparatus is disclosed in NL-A-161832 and improved embodiments of the same are disclosed in prior Dutch patent applications 8802565 to 8802567. Apparatus of this type are particularly suitable for forming mouldings for bricks having the characteristic "hand mould structure".
In general large numbers of moulding trays are involved, which are intermittently supplied to a loading station. Each station contains a large number, e.g. sixteen juxtaposed mould cavities. Usually the extruder comprises a number of presses with associated nozzles and depositing means, which number corresponds to half the number of the mould cavities in each moulding tray.
For example, the supply device for loading moulding trays containing sixteen juxtaposed moulding cavities comprises two rows of four extruders. Each row extending transversly to the direction in which the moulding trays are supplied. The extruders of one row are positioned laterally offset with respect to the extruder in the other row by a distance which corresponds to the pitch of the mould cavities. The extruders in each row are mutually spaced by a distance corresponding to twice the pitch of the mould cavities in the moulding tray. Each extruder is intended to load--one immediately after the other--two juxtaposed mould cavities of each moulding tray supplied. For this purpose the respective extruder and moulding tray must, after the first of said two juxtaposed moulding cavities are loaded, be displaced longitudinally relative to one another through a distance corresponding to the pitch of the mould cavities.
In the well-known systems, the extruding device usually has a stationary position and the moulding trays--after having received a first loading--are shifted in their longitudinal direction relative to the extruding device in order to receive the load for the second moulding cavity. A disadvantage of such a system is that the reciprocating movement of the moulding trays is produced over guideways which are usually covered with sand. As a result, the molding trays undergo a rapid abrasion which necessitates frequent changing of moulding trays. As an alternative it has been proposed to keep the moulding trays stationary, within the filling station, and to reciprocate the extruding device over a guide means, in the longitudinal direction of the moulding trays through a distance corresponding to the pitch of the mould cavities. This means that each time the extruding device is moved a very heavy mass has to be accelerated and decelerated along a very short distance.